How do I have the posts page as full width

My site is all set up and I’ve uploaded some images to it. I’ve changed a few things to remove the menu, the search box and to alter the footer.

However, I have reached my technical limit in forcing the posts page to be full width with no sidebar.

Can anyone help?

When I click on a post on the home page, it takes me to the single post. However, the sidebar is showing on the right for Archives and Meta. I have no widgets set up on the theme and I cannot find anywhere to select the default post page format.